It’s called i2Ninja and it can be used for a variety of nefarious purposes, including hijacking of FTP and email credentials and interception of web forms (affecting all the major web browsers). That’s some pretty nasty stuff, and it’s for sale on a Russian forum frequented by cybercriminals. Read more here:
http://www.securityweek.com/i2ninja-malware-kit-using-i2p-anonymity